my Sitemap, which is generated by XML Sitemap & Google News Feeds Plugin, is not working. Problem is that I have about 25.000 Posts stored in my WordPress Database - the sitemap just keeps loading and loading.

AFAIK, Quick Cache is supposed to help with WP installations with this size of content, it even says inside the Sitemap Plugin that Quick Cache is recommenend.

My Question now is, how can I enable the Sitemap Cache, since it seems not to be working?
Or if there is no "activate" switch for this, how can I find out why its not active already? Any typical problems that match to this case + solutions?